Episode Summary
Princess Lin'an experiments with refining silver but faces her mother's disapproval. Xu Qi'an is apprehended by the Watchmen and offered a chance to join their ranks. He chooses Yang Yan as his mentor and undergoes a series of tests, impressing everyone with his intelligence and rapid cultivation progress. He successfully becomes a watchman.

Spoiler Alert
The episode opens with Princess Lin'an, the Second Princess, nearly causing a catastrophic explosion at the Si Tian Jian (a historical government bureau for astronomy and calendar-making). She's attempting to refine tax silver, and despite the danger and difficulty, she's thrilled with her progress. However, her joy is short-lived. Back at the palace, her mother, Consort Chen, a stickler for tradition, expresses disapproval of women engaging in such "unladylike" pursuits, constantly comparing Lin'an unfavorably to the Crown Prince. This blatant favoritism leaves Lin'an feeling disheartened.
Meanwhile, Xu Qi'an, our quick-witted protagonist, is trying to make a discreet exit when he's intercepted by two "Watchmen" . Clearly prepared, they bundle Xu Qi'an into a carriage. He's racking his brains, trying to figure out if he left any loose ends when he took down the corrupt official Zhou Li. Thinking fast, he offers a bribe to one of the Watchmen, who simply advises him to keep quiet about anything he shouldn't.
The Watchmen take Xu Qi'an to their superior, Master Yang, where he also finds Nangong Qianrou. It turns out the Watchmen have been observing Xu Qi'an's entire scheme, recognizing his potential. He's given a choice: become the disciple of either Yang or Nangong Qianrou. Nangong Qianrou is particularly keen, using both charm and intimidation to sway him. But Xu Qi'an is no pushover. Remembering Yang Yan's past assistance, he chooses to apprentice under him as a gesture of gratitude.
But becoming a full-fledged watchman isn't that simple. Xu Qi'an must pass several tests, assessing his intelligence and inner resolve ("Wen Xin," literally "questioning the heart"). He breezes through the first test, answering a question in a mere three breaths – a shockingly fast time compared to his peers. He then ascends three levels of the building without performing the customary kowtow. He is warned about the punishment of lingchi (a gruesome form of execution) for not bowing by the fourth level. Xu Qi'an, startled, immediately prostrates himself. However, the magical "heart-reflecting mirror" still shows him standing, revealing his lack of genuine subservience.
Wei Yuan, the powerful head of the Watchmen, is intrigued by reports of Xu Qi'an's unusual performance. His rapid answers demonstrate intelligence, while his initial lack of deference suggests a fearless nature – qualities that could make him a great leader if properly cultivated.
Xu Qi'an reaches the sixth level, where he's presented with a poem by Wei Yuan. He quickly discerns Wei Yuan's ambition for power. As a modern man transmigrated into this world, Xu Qi'an isn't interested in political games, but he knows he needs to play along to become a watchman. He meticulously crafts a brilliant answer, earning the highest possible grade: "Jia Shang."
Nangong Qianrou is so impressed that she tries to buy Xu Qi'an from Yang Yan, offering two Silver Gong. Yang Yan, however, is determined to keep this promising recruit. He learns that Xu Qi'an has gone to the Marrow-Cleansing Pool, a crucial step in cultivating power, and personally enlists his brother-in-law, Li Yuchun, to mentor the newcomer.
Li Yuchun initially has a terrible impression of Xu Qi'an. He only agrees to observe him out of obligation to Yang Yan. To everyone's astonishment, Xu Qi'an completes the "Lian Qi Jing" (refining energy stage), a process that normally takes a full day, in less than an hour! This demonstrates his incredible potential and sets the stage for his future as a powerful watchman.